Diversity at the local scale is determined by different, and often interacting factors. One factor that is suggested to be important in determining community structure is productivity, which is related to diversity. Though this relationship might depend on different factors, a hump-shaped, U-shaped or positive linear relationship seems to be frequent at the local scale. On the other hand, the concept of metacommunity considers how several communities are linked through dispersal. Here, we experimentally assessed how primary producer biomass and dispersal barriers drive diversity at the local scale in Mediterranean streams. We did this by creating a reach scale study system that resembled a metacommunity. We found that higher primary producer biomass promotes a saturating relationship with diversity. However, we did not detect any effect of the dispersal barriers on the responses. Thus, our results show that, at the local scale, patch primary producer biomass plays a more important role in determining the community structure and colonization than dispersal barriers. In the framework of metacommunity theory, our study system can be explained by combining assumptions of the “Mass-Effects” and the “Species-Sorting” archetypes, supporting a non-exclusive view of these hypotheses.

中文翻译：

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地中海河流中生物多样性对扩散障碍和斑块初级生产者生物量响应的实验评价

地方范围内的多样性是由不同的、经常相互作用的因素决定的。建议在确定群落结构时重要的一个因素是生产力，它与多样性有关。虽然这种关系可能取决于不同的因素，但在局部尺度上，驼峰形、U 形或正线性关系似乎很常见。另一方面，元社区的概念考虑了几个社区如何通过分散联系起来。在这里，我们通过实验评估了初级生产者生物量和扩散障碍如何在地中海河流的局部范围内推动多样性。为此，我们创建了一个类似于元社区的覆盖范围研究系统。我们发现较高的初级生产者生物量促进了与多样性的饱和关系。然而，我们没有检测到分散障碍对响应的任何影响。因此，我们的结果表明，在局部范围内，斑块初级生产者生物量在确定群落结构和定植方面比分散障碍发挥更重要的作用。在元社区理论的框架内，我们的研究系统可以通过结合“质量效应”和“物种分类”原型的假设来解释，支持对这些假设的非排他性观点。